1. Field of the Invention
The present invention concerns a method to support the diagnosis and/or therapy of a pathological change of a blood vessel of a patient, in particular in the context of coronary heart disease, as well as a data processing device for such a purpose.
2. Description of the Prior Art
Blood vessels, in particular coronary blood vessels, for example coronary arteries, are affected by coronary heart disease, one of the main causes of death in the industrial nations. For example, over one million people in Europe and the USA died in the year 2000 as a result of a heart attack. The causes of coronary heart disease are atherosclerotic plaques in the coronary vessels that can lead to vasoconstrictions (narrowing) or vascular occlusion.
It is known that atherosclerotic plaques occur in various types with compositions different from one another. In general, they are differentiated by:                a) lipid-rich or non-calcified plaques, also designated as soft or “vulnerable” plaques: these types of plaques are associated with a particularly high risk for a coronary event (attack, sudden cardiac death), because with high probability, their rupture leads to an acute vascular occlusion, for example to a thrombotic occlusion or to an acute myocardial attack. The goal of the use of specific medicines, known as lipid suppressors, is the reduction of the risk of an acute coronary event that can lead to sudden cardiac death. The goal of the pharmacological therapy is the stabilization of potentially unstable plaques as well as the regression of advanced lesions. The effect of the lipid suppressors is currently not known in detail, such that the requirement exists to observe their effect in each individual case.        b) fibrous plaque: atherosclerotic plaques can change their composition, i.e. their type, over the course of time. A fibrous plaque represents a state between “lipid-rich” and “calcified” (see following) plaque.        c) calcified plaque: a plaque that has calcified—and likewise also a fibrous plaque—is in general stable and seldom causes acute vascular occlusion.        
A need thus exists to detect an existing plaque in a patient in order to be able to evaluate the risk associated therewith as to the occurrence of coronary events. One method for detection of calcified plaques in the coronary arteries is described in the professional article by Agatston A. S., Janowitz W. R., Hildner F. J., Zusmer N. R., Viamonte M., Detrano R., “Quantification of coronary artery calcium using ultrafast computed tomography”, Journal of the American College of Cardiology (1990), volume 15, pages 827-832. Electron beam computed tomography (EBCT) is used as an imaging method. The detection of non-calcified plaques with EBCT can currently not be achieved due to the severely limited contrast resolution.
The detection of non-calcified coronary plaques is possible, for example, using the technique of intravascular ultrasound (IVUS). A running differentiation of atherosclerotic plaques (but only indirectly by a determination of wall thickness) also can ensue by means of magnetic resonance tomography. Such a method is specified in the professional article by Fayad A. A., Fuster V., Fallon J. T., “Non-invasive in vivo human coronary artery lumen and wall imaging using black-blood magnetic resonance imaging”, Circulation (2000) volume 102, pages 506-510.
The newest generation of the multi-slice (multi-layer) computed tomography devices (MDCT) likewise allow the non-invasive depiction of the coronary arteries. With regard to this, electrocardiogram-synchronized (ECG-synchronized) acquisition techniques are described in the professional article by Ohnesorge B., Flohr T., Becker C. R., Kopp A. F., Knez A., Baum U., Klingenbeck-Regn K., Reiser M. F., “Cardiac Imaging by Means of Electrocardiographically Gated Multisection Spiral CT: Initial Experience”, Radiology (2002), volume 217, pages 564-571. As is presented in the professional article by Becker C. R., Ohnesorge B., Schöpf U. J., Reiser M. (2002c), “Current Development of Cardiac Imaging with Multidetector-Row CT”, European Journal of Radiology (2000), volume 36, pages 97-103, the depiction of calcified and non-calcified plaques with multi-slice computer tomography is possible on the basis of approximate isotropic section cross-section data sets. In the professional article by Schröder S., Kopp A. F., Baumbach A., Küttner A., Georg C., Ohnesorge B., Herdeg C., Claussen C. D., Karsch K. R., “Non-invasive Detection and Evaluation of Atherosclerotic Plaque with Multi-Slice Computed Tomography”, Journal of the American College of Cardiology (2001), volume 37, pages 1430-1435 it is disclosed that lipid-rich, fibrous and calcified plaques can be differentiated via measurement of the CT density values.